rainwater harvesting

has anyone intalled such a system? I have a 1200l tank and am going to be using a submersible pump to pump water to a header tank for the toilet cistern. as the tank is above ground and will be susceptible to frost etc I am wodering what type of water pipe I could use. plastic would be easier as I can run it in as one length. we live in a bungalow and cannot dig up the concrete patio to sink pipes underground. any help or advice appreciated.

dave

Reply to
dave
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Most types of plastic are pretty tolerant of freezing. The other issue might be UV if it sees sunlight (that said, I have a garden hose tap with mains pressure on a temporary run of (I think) PVC which has been fine for the last 15 years. How long is the run? Does it see sunlight? Could you protect it with say foam pipe insulation? I'd be inclined to run it how it is most convenient and inconspicuous and accept that you might (just possibly) have a failure in a real arctic winter or after 20 years of sunlight. Even a failure is quick, cheap, and easy to fix with pushfit. If you have a very long run you might give the pump an easier time by using 22 or 25 mm instead of 15 mm.

Reply to
Newshound

I used the blue MDPE water pipe from Screwfix for the main runs for my irrigation system. (I can't link to it, it is down for maintenance as I type!) I then got all my connectors/adaptors etc. from a local irrigation supplier (City Irrigation in Bromley -

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I got all my sprinkler heads/drippers etc from here
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They seemed to be the cheapest, the service was excellent too.

I have got a small header tank ready to go in the loft for exactly the same reason.

I will be fitting two ball valves in this tank, one set so the ball it near the top of the tank, the other about 1/3 of the way up, the top one will be connected to the rainwater supply, and the other to the mains. This way, if the rainwater dries up, it will automatically revert to mains.

I bought a 3 bar pump from eBay (it actually came from pump.co.uk) and have connected a one way valve to it's outlet, then a flow switch, then a pressure switch, then a pressure vessel. It is wired so if the pressure switch is not satisfied the pump turns on, then only turns off when the flow has stopped and the pressure switch is satisfied there is enough pressure. There is also a float switch in the barrel the pump is in, so it doesn't run if the water level is too low. this makes the pump fully automatic. I probably should include a temperature sensor, so it doesn't run if the water temperature is

Reply to
Sparks

If theyre at different levels, the mains will only fill it 1/3 full and it wont work. To have automatic mains backup, there are 2 ways to do this.

  1. Have both cistern fill valves set to same level, but with the mains one set to a slow fill and the rain to faster fill
  2. Use a float valve in the rain header tank. If the tank falls to
10-20% then mains water tops it up to that 20% mark.

Pressurised may work for a ground level header tank, but for a loft header its unnecessary complication, extra failure points & cost.

Whatever pump is used, check its head spec. May pumps will have insufficient head for this app.

Another simpler setup is to lose the 2nd cistern fill valve and use an electrical float switch. This runs the pump which is plumbed direct to the cistern. No header tank, no piping for it, no loft access etc.

A filter on the rain tank inlet will keep detritus out and reduce detritus decomposition in the tank.

NT

Reply to
meow2222

Correct, it will fill to 1/3, why won't this work, the outlet to the toilets will be right at the bottom, what will stop the water from draining into the toilet cistern?

So you are not using 100% rainwater...

  1. Do what I suggested, I fail to see why it won't work.

The rainwater is stored in 5 x 1000l and 2 x 1500l tanks/barrels, I ain't gonna put all this in the roof!

The OP also has a 1500l tank/barrel, so would need a pump.

3 Bar = 30M

Unless you want to use the same pump for other purposes, like another toilet or watering the garden!

I do have this, and then a finer fiter on the outlet.

Sparks...

Reply to
Sparks

I guess you meant your float valve is in the header tank, I thought you meant in the bog cistern.

You will of course have to mount both valves above the high water mark and just bend the float on one, otherwise the supply outlet would be below the water line, which is an illegal health risk. Unless you also add a double check valve.

No, but nearly. On the other hand you've got much lower system cost. Of course you can have a hand operated valve on the mains feed, but then its not fully automatic.

it will. Whether its an optimised design is another question.

the idea was to put a small unpressurised header tank in the loft, not the main storage tank. It only need hold enough for a couple of flushes.

yes, not for a 2 toilet system. Using that setup for garden watering is no prob though.

Youre trapping the fine stuff instead of flushing it through? I guess you have to if you're using water valve control.

The choice between direct or header tank really depends whether you've got more than one rain using appliance, but the choice to go pressurised seems an unnecessary expense and source of possible failures to me. Still will work though, long as you dont spring a leak :)

NT

Reply to
meow2222

some interesting points here. I will only be using the water for a toilet. my idea was to go through the loft as it is easiest for me to do. I wanted to have mains water back up but have been concerned about contamination of the mains supply if I have no rainwater. I was thinking of fitting a non return valve and mains water at the toilet cistern along with the rain water in a simple "T". the mains water would be controlled by a stop tap as this will be located near to the toilet itself so no climbing into the loft to changeover. I want to do this on a budget. I have looked at an electronic pressure switch from pump.co.uk. this will automatically switch the pump when the chain is flushed, it also gives protection to stop the pump running dry when there is no water in the tank. Dave

Reply to
dave

Have you got any of the bits yet, pump etc?

Sparks...

Reply to
Sparks

---cut----

I am awaiting delivery of my loft tank kit. I will be visiting screwfix for pipe in the next day or 2. I looked at a simple manual pump from screwfix (65845) and thought this would be ideal, I can always upgrade/date later if needed. we do have trade places where I can try and get a non return valve.

Dave

Reply to
dave

Is that pump going to be "man" enough, it's only 0.8 bar (It will *just* pump to 8m when using large bore pipe...

Not sure of your budget, but here is some other ideas...

Pump (3.7 Bar) £50

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Vessel (You will need to check this will handle 4 bar, I expect it will)
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Switch
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Switch
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Switch (To control the pump, so it doesn't run when the is insufficient water in your main storage)
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(I expect you will need to connect the pump to this (and the flow & Pressure switch via a relay, as a pump draws quite a bit of current when it starts)

Sparks...

Reply to
Sparks

thanks for info sparks. I was looking at an all in one control unit from pumps.co.uk (PRODUCT CODE: 060-430). I had not thought of the pump pressure until you have mentioned it. Yes the ebay one may be better but a submersible one would be preferred. As I have not started the installation yet I have time to alter or update what I require/want.

dave

Reply to
dave

I might have missed something here but don't you need an air gap rather than a non-return valve?

Mary

Reply to
Mary Fisher

There are for and against for a submersable pump.

The good thig is, it lives in the barrel, so it is hidden away

Bad thing is, if the water level is quite low, it can over-heat.

I have a submersable one, but wish I had an external one now, as it has tripped its overheat stat a couple of times (I will probably just divert some of the flow so it pours over the pump to rectify this)

Also, I found the level switches on the submersable pump to be pretty usless for my needs, they will switch the pump off when the level is too low perfectly, but then take ages (loads of water) to then turn on again - I have tied the level switch attached to my pump up, so it doesnt activate, and am using the little sensors I linked to earlier to deal with the water levels.

It looks like the Presscontrol 230v Electronic Pressure Switch you mentioned would do the job of the water level switch, the pressure switch and the flow switch, however, it looks like it would need a manual reset if the pump ran dry, that could be a pain, my way will automatically reactivate when the rain comes :)

Sparks...

Reply to
Sparks

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